Replace icon for Posit AI so that it aligns with brand identity. cc @alex-chisholm <img width="104" height="114" alt="Image" src="https://github.com/user-attachments/assets/ba87ff2a-37a9-4a79-a8d4-80f70f813405" /> <img width="172" height="67" alt="Image" src="https://github.com/user-attachments/assets/52fa1c60-86c4-4ae5-8b69-abbac10a352b" />
Replace icon for Posit AI so that it aligns with brand identity.
cc @alex-chisholm